1. Field of the Invention
The present invention relates to an image blur correction unit, a lens barrel device, and a camera apparatus each correcting an image blur caused by a vibration upon shooting.
2. Description of the Related Art
Compact cameras are being requested to be further reduced in size and have higher power (magnification) and higher pixel resolution. Accordingly, this leads to an increased frequency of capturing an image blurred due to camera shake upon shooting a subject. As for a mechanism for shifting an optical element to compensate for camera shake, a retractable optical system and an optical-axis bending optical system each include a mechanism axially sliding in two directions. For example, in a related-art mechanism, the center of gravity of an optical element is disposed within an area surrounded by four guide shafts axially sliding in two directions.
For example, in an image blur correction unit disclosed in Japanese Unexamined Patent Application Publication No. 3-188430 (U.S. Pat. No. 5,266,988), a lens holding frame which holds a correction lens is held by a first holding frame having a pair of pitch shafts such that the lens holding frame is movable in the pitch direction. The first holding frame is supported by a second holding frame having a pair of yaw shafts such that the first holding frame is movable in the yaw direction. The correction lens held by the lens holding frame is located in an area surrounded by the pair of pitch shafts and the pair of yaw shafts. Actuators moving in the pitch direction and actuators moving in the yaw direction are each configured such that magnets and a yoke form a magnetic circuit and a coil is disposed in the magnetic circuit. Those actuators generate propulsive forces in the pitch direction and the yaw direction, respectively, using magnetic fields generated by currents flowing through the coils.
In the unit disclosed in Japanese Unexamined Patent Application Publication No. 3-188430, the actuators for driving the correction lens in the pitch direction and the other actuators for driving the correction lens in the yaw direction each have to include the magnets and the yoke. In addition, those actuators are arranged so as to surround the correction lens. Accordingly, the size of the image blur correction unit is increased in the direction orthogonal to the optical axis of the correction lens, thus upsizing a lens barrel and the whole of a camera and increasing the number of components. This leads to an increased cost.
In an optical-axis bending lens system in which the optical axis is bent at an angle of 90 degrees, if a correction lens is disposed in an area surrounded by four shafts in a manner similar to Japanese Unexamined Patent Application Publication No. 3-188430, it is difficult to reduce the thickness of a lens barrel, namely, further reduce the thickness thereof in the direction along the optical axis.
Assuming that the correction lens is disposed in the area surrounded by the four shafts, in order to reduce the size or thickness of a camera, an opening of a holding frame has to be sufficiently larger than the optical effective aperture. Upon reducing the size or thickness of the camera, however, it is difficult to ensure that the opening is sufficiently larger than the optical effective aperture. Disadvantageously, a stray light component may enter the optical path, thus causing a ghost image.